For mobile terminals such as mobile phones, for example, a variety of input devices allowing users to operate the terminals have been developed according to the function and usage of each of the terminals. Often, the input devices are configured such that a user performs an input operation by directly depressing mechanical keys or buttons, prearranged on the surface of the body of the mobile terminal, with a finger or the like.
Such mechanical keys (for example, a numeric keypad) of the input device in the terminal are normally prearranged to suit the primary usage of the terminal. Accordingly, the initially prescribed physical arrangement of such keys cannot generally be changed afterward.
Recently, a variety of functions have been incorporated into small mobile terminals, such as a digital camera function and a music player function incorporated into mobile phones. Like mobile phones, some terminals have numerous supplementary functions incorporated therein in addition to the main usage of the terminal, whereas some single terminals, including PDAs (Personal Digital Assistant: mobile information terminal), smartphones, and tablet terminals have a plurality of main usages such as schedule management, an address book, and the like. If the keys of such terminals are fixedly arranged, it may inconvenience users significantly when performing an input operation, depending on the function used.
In order to resolve such inconvenience during input operations, some input devices such as an operation unit, switches, or the like for detecting an input operation by the user are provided with a touch sensor such as a touch panel, touch switch, or the like (for example, see Patent Literature 1). The input device having such a touch panel generally displays images of operation keys, buttons, or the like, as well as a character or character string to prompt for user input (referred to below as an “object”) on a display screen of the touch panel. When the user presses an object displayed on the display screen, an input unit (touch sensor) at a corresponding position on the touch panel detects the contact.
A variety of types of such a touch sensor are known, including a resistive film type, a capacitive type, and an optical type. All of these types of touch sensors, however, simply detect contact by a finger or stylus pen. Upon being contacted, the touch sensor itself is not physically displaced like a mechanical push-button switch.
The mobile phone described in Patent Literature 1 can display objects arranged in a desired manner on the display screen of the touch panel and detect contact by the user. This mobile phone also allows for free arrangement of keys and the like. Accordingly, when switching between functions of the terminal, this mobile phone can provide excellent operability by freely changing the arrangement of the objects to suit the functions. For example, when the user uses the digital camera function incorporated into the mobile phone, the mobile phone can display an object constituting an operation unit of a digital camera on the touch panel and detect user operation. By contrast, when the user inputs characters for an e-mail or the like using the mobile phone, the mobile phone can display an object constituting a keyboard similar to that of a personal computer (PC) on the touch panel and detect contact. In this way, by including the touch panel, this mobile phone can detect a user operation while optimizing a single input device for each of a plurality of functions.
In addition, since the input device including the touch panel detects contact by the user directly contacting (touching), with a fingertip or the like, an object displayed on the display unit, the user can perform operations in a highly intuitive manner. In other words, the user performs operations by directly contacting, with a fingertip or the like, the object displayed on the screen, following guidance displayed on the screen of the touch panel. Accordingly, the user can cause the terminal to execute processing extremely easily with an intuitive operation, following the guidance displayed on the screen. Hence, an effect of reducing erroneous operations can be expected.
Since a touch panel thus has the advantages of enhancing flexibility in configuring the input unit and of allowing the user to perform an input operation in a highly intuitive manner, the number of the terminal devices including an input device provided with such a touch panel is increasing.
Input devices having the above-described touch panels are now commonly used not only in mobile terminals, but also, for example, Automatic Teller Machines (ATMs) at banks and the like, and ticket vending machines at places such as train stations. Additionally, in stores such as fast-food shops, clerks use terminal devices provided with an input device having the above-described touch panel to process orders from customers. Using the touch panel in the input device eliminates the need for mechanical operation buttons or keys, such as a keyboard separate from the touch panel. Accordingly, since only a small area on the body of the terminal device is required for arrangement of mechanical buttons and the like, the terminal device can be reduced in overall size. Therefore, the degree of freedom for the location to install the terminal device in shops, train stations, and the like increases.